What Is Magnesium?
Magnesium is a mineral that plays a big role in making your body work right. More than 300 chemical reactions inside you depend on the mineral.
Without it, your muscles can't move the way they're supposed to. Your nerves won't send and receive messages. Magnesium also keeps your heart rhythm steady, blood sugar levels balanced, and your joint cartilage healthy. It helps your body make protein, bone, and DNA.
Your body doesn't make magnesium on its own. The amount you need depends on your age and gender. If you're a woman age 19 or older, you need 310 milligrams a day -- 350 milligrams if you're pregnant. If you're an adult man under age 30, you need 400 milligrams a day. After 30, men need 420 milligrams.
Where to Get Magnesium
It's always best to get magnesium from food, but you can also get it from multivitamins and supplements.
Because the kidneys filter out excessive amounts of magnesium, it’s unusual for a healthy person to suffer from getting too much magnesium from foods they eat. If you take supplements, don’t take more than the upper limit unless your doctor recommended it. Getting too much magnesium can cause diarrhea, nausea, and abdominal cramps. Extremely high doses can lead to irregular heartbeat and heart attacks.
Don't take a magnesium supplement if you have certain conditions, such as:
- Heart block
- Kidney failure
- Bowel obstruction
- Myasthenia gravis
Certain conditions like Crohn's disease, celiac disease, type 2 diabetes, alcoholism, and chronic diarrhea can give your body a long-term shortage of magnesium. Common symptoms include loss of appetite, nausea, vomiting, and fatigue.
Foods With Magnesium
Many types of foods contain magnesium. These include leafy green vegetables, whole grains, beans, nuts, and fish.
Fish for Magnesium
These types of fish provide magnesium:
- Atlantic mackerel
- Atlantic pollock
Vegetables and Fruits That Have Magnesium
Prickly pear has a lot of magnesium, but it isn't the easiest food to find or prepare.
Focus instead on these fruits and vegetables that have a lot of magnesium when you cook them and plenty of other nutrients, too:
- Swiss chard (and other leafy green vegetables)
- Potato with skin
Whole-Grain Products With Magnesium
Look for breakfast cereals fortified with magnesium and these whole grains:
- Bran cereals
- Wheat germ
- Brown rice
Legumes, Nuts, and Seeds With Magnesium
Meat and poultry don't have a lot of magnesium, but you can find it in soy, cheese, and yogurt.
These meat alternatives are also good magnesium sources:
Magnesium in Water
Depending on the source and brand, water may contain a small amount of magnesium.
Certain food products have added magnesium, but you need to look at the label to be sure. Some examples are:
- Meal replacement bars
- Protein powders
- Weight loss shakes
Some medicines may keep your body from absorbing magnesium, such as:
- Bisphosphonates for osteoporosis
- High doses of zinc
If you take water pills or some medicines for acid reflux or peptic ulcers for a long time, they can lower your magnesium levels, too.
Less chance of high blood pressure: Magnesium supplements, in people with high blood pressure, notched down their blood pressure by a few points (3-4 points in systolic blood pressure, which is the top number in a BP reading, and 2-3 points in diastolic blood pressure, which is the bottom number in a BP reading). Getting more magnesium from foods was linked to a bigger drop in blood pressure. The DASH diet, which helps lower blood pressure, gives you all the magnesium and other nutrients you need. With foods, you get many vitamins and minerals so it’s hard to tease out exactly how much the magnesium alone helped.
Less chance of stroke, heart disease, and type 2 diabetes: A review of multiple clinical studies found that increased magnesium levels were linked to a lower risk of heart disease.
Another research review focused on stroke risk and found that people who got more magnesium from their diet had a lower risk of stroke (especially stroke caused by clots). There’s a chance that other nutrients also played a role in that.
As for type 2 diabetes, it’s less common in people whose diet is rich in magnesium. The same caveat applies with diet – foods deliver a lot of nutrients so it’s hard to isolate just one. On the other hand, there’s no downside to eating foods that are rich in magnesium as part of an overall healthy lifestyle. The American Diabetes Association has said that there’s not enough evidence to support magnesium supplementation to help with blood sugar control in people with diabetes.
Less severe asthma attacks? Because magnesium helps muscles relax, it may lessen asthmatic spasms. But this was magnesium given by IV, not what you’d get from food or supplements.
Fewer migraines, possibly:Some people who get migraines have low levels of magnesium. But the effectiveness of magnesium supplements in helping people deal with migraines is still questionable. There have only been small studies on this, and the effect is modest. You should only consider supplements for this reason if your doctor recommends it. They might consider it if the main medications and traditional treatments don’t help.
Mental health benefits? Magnesium levels are low in some people with certain mental health conditions, including depression. A 2020 review of research on whether supplementing magnesium in addition to other treatments had mixed results. Magnesium supplementation “could be beneficial,” the researchers wrote, noting that studies are needed to find out if magnesium is effective alone or with antidepressants.
Stronger bones after menopause: There haven’t been a lot of studies on this topic, but the National Institutes of Health notes that research shows that boosting magnesium from food or through supplements may increase bone mineral density in women after menopause. Exactly how much you’d need is not clear. A healthy diet does support bone health.
Amounts and Dosage
The recommended daily allowance of magnesium varies by age, gender, and whether you’re pregnant or breastfeeding. Again, foods are the best source. If you take supplements, check the label to see how much magnesium is present, and check with your doctor to make sure that it’s OK for you to take.